According to an art disclosed in Japanese Patent Application Publication No. 2011-230260 (JP 2011-230260 A), an abutment member having an inner bag that is filled with a particulate matter and an outer bag that covers the inner bag is provided at a tip of a gripping portion of a gripping device. After the abutment member is deformed along the contour of a work, air is removed from the inner bag. Thus, the abutment member is hardened while maintaining the shape thereof. Besides, the enhancement of durability is achieved by fabricating the outer bag from a woven cloth made of aramid fiber.